One key challenge in the numerical simulation of aeroacoustic fields is the huge disparity of scales between flow structures and audible acoustic wavelengths. A volume discretization, resolving both scales from the generating vortex to the desired microphone position, not only leads to a very high number of cells but also to a very small time step size in order to minimize dissipation of the ac...

We study the propagation of an acoustic wave in a moving fluid in the high frequency regime. We calculate a high-frequency approximation of the solution of this problem using an Eulerianmethod. The model retained is a linearized Euler system around a mean fluid flow. For any regular mean flow, we derive a conservative transport equation for the geometrical optics approximation. We introduce the...

The performance of several non-reflective acoustic boundary conditions is quantitatively compared using a plane wave test configuration. The study uses a high-order linearized Euler equation solver to find a non-reflective boundary condition which gives good performance in a variety of cases. The performance for acoustic waves with varying frequency and incident angle is compared in flows with ...

The purpose of this paper is to characterize and model waves that are observed within the potential core of subsonic jets and that have been previously detected as tones in the near-nozzle region. Using three models (the linearized Euler equations, a cylindrical vortex sheet, and a cylindrical duct with pressure release boundary conditions), we show that these waves can be described by linear m...

Leading edge noise is a significant broadband noise source in aircraft engines, and is the primary broadband noise mechanism in outlet guide vane noise in turbofans, and broadband rotor wake interaction noise in contra-rotating open rotor engines. Previous authors have studied the effects of various aspects relating to this noise source, including airfoil geometry effects, cascade effects, and ...

Abstract The study provided a base of comparison known computational techniques with different fidelity levels for performance and noise prediction single, fixed-pitch UAV rotor operating varying flight parameters. range aerodynamic tools included blade element theory, potential flow methods (UPM, RAMSYS), lifting-line method (PUMA) Navier–Stokes solver (FLOWer). Obtained loading distributions ...